[Comparative activity of ticarcillin-clavulanic acid and various beta-lactams against Pseudomonas maltophilia].

An increase is observed in the isolation of P. maltophilia as a casual agent of nosocomial infection, particularly in hospitalized immunocompromised patients. These infections are associated with the acute problem of their treatment as most of the P. maltophilia strains are generally resistant to many of the commonly used antimicrobial agents, including those active against Pseudomonas aeruginosa: beta lactams, aminoglycosides and imipenem. This resistance is correlated with two inducible beta lactamases (L1, pI = 6.9; L2, pI = 8.4). Azlocillin, piperacillin, cefoperazone, ceftazidime, latamoxef, ticarcillin, ticarcillin and clavulanic acid in combination were tested against 93 P. maltophilia isolates by disk diffusion testing and agar dilution technique. The association of clavulanic acid with ticarcillin resulted in better MIC values for ticarcillin (MIC 50 = 32, MIC 90 = 128). 96% of strains were sensible to the breakpoint of 128 mg/l. Other beta lactam antibiotics showed a loss of activity except for latamoxef (67% of strains susceptible to 4 mg/l) which is a potent inhibitor of both beta-lactamases. According to these results, the combination of clavulanic acid with ticarcillin may be useful in the treatment of P. maltophilia acquired hospital infections.